99 lines
1.3 KiB
ArmAsm
99 lines
1.3 KiB
ArmAsm
; Checkers
|
|
; vaguely based on a scene in Hellmood's Memories
|
|
|
|
; 32 bytes, for Lovebyte 2021
|
|
|
|
; by deater (Vince Weaver) <vince@deater.net>
|
|
|
|
; 42 -- original
|
|
; 39 -- not fullscreen
|
|
; 36 -- now marches oddly
|
|
; 32 -- colors now rainbow
|
|
|
|
; Zero Page
|
|
BASL = $28
|
|
BASH = $29
|
|
H2 = $2C
|
|
COLOR = $30
|
|
|
|
X1 = $F0
|
|
X2 = $F1
|
|
Y1 = $F2
|
|
Y2 = $F3
|
|
|
|
TEMP = $FA
|
|
TEMPY = $FB
|
|
FRAME = $FC
|
|
TEMPX = $FD
|
|
|
|
|
|
; Soft Switches
|
|
KEYPRESS= $C000
|
|
KEYRESET= $C010
|
|
SET_GR = $C050 ; Enable graphics
|
|
FULLGR = $C052 ; Full screen, no text
|
|
PAGE0 = $C054 ; Page0
|
|
PAGE1 = $C055 ; Page1
|
|
LORES = $C056 ; Enable LORES graphics
|
|
|
|
; ROM routines
|
|
|
|
PLOT = $F800 ; plot, horiz=y, vert=A (A trashed, XY Saved)
|
|
SETCOL = $F864
|
|
TEXT = $FB36 ;; Set text mode
|
|
BASCALC = $FBC1
|
|
SETGR = $FB40
|
|
HOME = $FC58 ;; Clear the text screen
|
|
WAIT = $FCA8 ;; delay 1/2(26+27A+5A^2) us
|
|
HLINE = $F819
|
|
|
|
|
|
.zeropage
|
|
|
|
checkers:
|
|
|
|
;===================
|
|
; init screen
|
|
jsr SETGR ; 3
|
|
; bit FULLGR ; 3
|
|
|
|
checkers_forever:
|
|
|
|
inc FRAME ; 2
|
|
|
|
ldx #39 ; 2
|
|
yloop:
|
|
ldy #39 ; 2
|
|
xloop:
|
|
|
|
; calculate color
|
|
|
|
; color = (XX-FRAME)^(A) | DB+1
|
|
|
|
; sec ; subtract frame from Y
|
|
tya
|
|
sbc FRAME
|
|
sta X2
|
|
|
|
txa
|
|
; sbc #0
|
|
|
|
eor X2
|
|
|
|
; ora #$DB ; needed for solid colors
|
|
; adc #1
|
|
|
|
jsr SETCOL
|
|
|
|
txa ; A==Y1 ; 1
|
|
jsr PLOT ; plots in (Y,A) ; 3
|
|
|
|
dey ; 1
|
|
bpl xloop ; 2
|
|
|
|
dex ; 1
|
|
bpl yloop ; 2
|
|
|
|
bmi checkers_forever ; 2
|
|
|